Končitíková, R., Vigouroux, A., Kopečná, M., Andree, T., Bartoš, J., Šebela, M., Moréra, S., Kopečný, D.
BIOCHEMICAL JOURNAL
468:
109-123,
2015
Keywords:
aldehyde dehydrogenase 2 (ALDH2), aldehyde dehydrogenase 7 (ALDH7), benzaldehyde, coniferaldehyde, cytokinin, fertility restorer
Abstract:
Aldehyde dehydrogenases (ALDHs) are responsible for oxidation
of biogenic aldehyde intermediates as well as for cell
detoxification of aldehydes generated during lipid peroxidation.
So far, 13 ALDH families have been described in plants.
In the present study, we provide a detailed biochemical
characterization of plant ALDH2 and ALDH7 families by
analysing maize and pea ALDH7 (ZmALDH7 and PsALDH7)
and four maize cytosolic ALDH(cALDH)2 isoforms RF2C,
RF2D, RF2E and RF2F [the first maize ALDH2 was discovered
as a fertility restorer (RF2A)]. We report the crystal structures
of ZmALDH7, RF2C and RF2F at high resolution. The
ZmALDH7 structure shows that the three conserved residues
Glu120, Arg300 and Thr302 in the ALDH7 family are located in
the substrate-binding site and are specific to this family. Our
kinetic analysis demonstrates that α-aminoadipic semialdehyde,
a lysine catabolism intermediate, is the preferred substrate
for plant ALDH7. In contrast, aromatic aldehydes including
benzaldehyde, anisaldehyde, cinnamaldehyde, coniferaldehyde
and sinapaldehyde are the best substrates for cALDH2. In line
with these results, the crystal structures of RF2C and RF2F reveal
that their substrate-binding sites are similar and are formed by an
aromatic cluster mainly composed of phenylalanine residues and
several nonpolar residues. Gene expression studies indicate that
the RF2C gene, which is strongly expressed in all organs, appears
essential, suggesting that the crucial role of the enzyme would
certainly be linked to the cellwall formation using aldehydes from
phenylpropanoid pathway as substrates. Finally, plant ALDH7
may significantly contribute to osmoprotection because it oxidizes
several aminoaldehydes leading to products known as osmolytes.
Fulltext: contact IEB authors
IEB authors: Jan Bartoš
